Tentacools and Tentacruels are often found while Surfing. Try areas around Pastoria City.
In the national pokedex it's tentacool, and in the pearl pokedex it's misdreavus.
Pokemon 72 is Tentacool.
Certain Pokemon learn it by leveling up, such as tentacool. There is no TM and no Tutor, so you might want to check serebii.net's attackdex to find out what Pokemon can use it and how they learn it.
Tentacool evolves into a Tentacruel at level 30.
Tentacool evolves on Lvl. 30 into Tentacruel.
In Pokemon Diamond, Pearl, and Platinum you can find Tentacool in almost any large body of water. Once you get the move Surf from the Pastoria Gym go back to Sandgem town. You have to teach a Pokemon surf first, pretty much all Water type Pokemon can learn it. Then go down to the beach and use surf in the water. Swim around a bit and you're bound to run into a Tentacool.
Tentacool are one of the most common Pokemon found while surfing on nearly any route. They are also common fishing with the old or good rods.
tentacool
Tentacool evolves at level 30 into Tentacruel.30
In diamond is TENTACOOL but I am not sure about in other Pokemon games. In diamond is TENTACOOL but I am not sure about in other Pokemon games.
Tentacool: 461r3t44
Tentacool: 461r3t44